1. Field of the Invention
The invention relates in general to a multi-domain vertical alignment (MVA) liquid crystal display (LCD), and more particularly to an MVA thin-film transistor (TFT) LCD with sub-pixel electrodes driven by data signals in different electrical polarities.
2. Description of the Related Art
Recently, the MVA LCD has attracted a lot of interest because of its characteristics, such as superior viewing angle and high display quality. A cross-sectional view of a first conventional MVA LCD is illustrated in FIG. 1A. An electrode 2a is formed on a substrate 1a, and projection patterns 3a formed of insulating material are formed on the electrode 2a. The electrode 2a and the projection patterns 3a are covered with a vertical alignment film 4a. An electrode 2b is formed on another substrate 1b, and projection patterns 3b formed of insulating material are formed under the electrode 2b. The electrode 2b and the projection patterns 3b are covered with a vertical alignment film 4b. 
Due to the projection patterns 3a and 3b, some of the liquid crystal molecules 5 are oriented perpendicularly, while others, especially those over the projection patterns 3a and 3b, are tilted at an angle with respect to the surface of the alignment film when no voltage is applied across electrodes 2a and 2b. When the voltage is applied across electrodes 2a and 2b, the liquid crystal molecules 5 located near the projection patterns 3a and 3b may affect the inclinations of the liquid crystal molecules 5 apart from the projection patterns 3a and 3b. That is, the liquid crystal molecules 5 are inclined oppositely on both sides of the projecting patterns 3a and 3b. In this way, the liquid crystal molecules 5 automatically are divided into two re-orientation statuses to create two domains with opposite viewing characteristics; thus, MVA LCD with wide viewing angles is obtained.
The projection patterns 3b can be replaced by slits 6, as shown in FIG. 1B. The electrode 2b in FIG. 1A is divided into electrodes 2b′ and 2b″ in FIG. 1B, wherein the electrodes 2b′ and 2b″ are electrically connected and supplied with the same voltage. Since the direction of the electric field in the neighborhood of the slits 6 is slightly inclined (as dotted lines shown in FIG. 1B) with respect to surfaces of the electrodes 2b′ and 2b″ when a voltage is applied to both the electrodes 2b′ and 2b″, the liquid crystal molecules 5 near the slits 6 are inclined to different directions. Thus, two domains are formed as the LCD shown in FIG. 1B.
Unfortunately, the intensity of the lateral field between the electrodes 2b′ and 2b″ are insufficient because the electrodes 2b′ and 2b″ are electrically connected, and supplied with the same voltage. That is, the electric field which inclines the LC molecules is not strong enough to affect the re-orientation effectively. As a result, the response time of the LC molecules is poor and can not be reduced effectively.